Live offspring have been born to sheep whose ovaries had been removed, cut in half, frozen, thawed and then grafted back.
The researchers hope the research will offer 鈥渋mmense hope鈥� to women who are at risk of losing their fertility due to cancer therapy, for example. But a very similar technique also produced live lambs in 1994 but has not yet led to advances in human medicine, despite a number of attempts.
The most recent work, by Bruno Salle鈥檚 team at the H么pital Edouard Herriot in Lyon, France, cut the ovaries in half before freezing and then regrafting. In the earlier work, David Baird of the University of Edinburgh and colleagues cut the ovaries into strips.
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Stephen Shalet of Christie Hospital in Manchester has performed ovarian grafts on women and told快猫短视频: 鈥淵ou could argue that using [half ovaries], the tissue might function for longer so you would not need to repeat the procedure so often 鈥� but it isn鈥檛 really an advance of concept.鈥�
So far, these in women the grafts have worked only for a very short time. One patient did ovulate once, but this has not been repeated.
Overall, the technique has been 鈥渄esperately disappointing鈥� in women, says Simon Fishel, an expert in reproductive medicine at the Park Hospital in Nottingham.
Early deaths
Four of six ewes treated by Salle鈥檚 team became pregnant. Although three lambs died after birth, three are healthy. Salle believes the deaths were due to chance, and not a result of the procedure.
Between September 1999 and January 2000, Salle鈥檚 team removed one ovary from each of the six ewes. They cut the ovaries in half, froze them down to -196 掳C and stored them in liquid nitrogen for between one and three months.
After rapid thawing, the sections were incubated at 37 掳C for half an hour and regrafted into the sheep.
Tests showed that all the previously frozen ovaries were working normally between two and four months after the grafting.
This research was presented at the European Society for Human Reproduction and Embryology conference in Lausanne, Switzerland.